Block ICU data override with loading from file

This is a v8-port of
https://chromium-review.googlesource.com/c/chromium/src/+/890176 .

By default, ICU tries to load data items (e.g. brkitr/char.brk)
from individual files before trying the common data. Because
all the ICU data Chrome needs is included in the common ICU data file
that is memory mapped in InitializeICU(), trying to load from the
disk just wastes cycles because there's no file with separate ICU data
items.

Bug: chromium:805694
Test: Intl tests
Change-Id: Ia7e77d658b56d98027336acd2c91fd5f7b2cea3e
Reviewed-on: https://chromium-review.googlesource.com/890343Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jungshik Shin <jshin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50939}

src/icu_util.cc

@@ -81,6 +81,8 @@ bool InitializeICU(const char* icu_data_file) {
 
   UErrorCode err = U_ZERO_ERROR;
   udata_setCommonData(reinterpret_cast<void*>(addr), &err);
+  // Never try to load ICU data from files.
+  udata_setFileAccess(UDATA_ONLY_PACKAGES, &err);
   return err == U_ZERO_ERROR;
 #elif ICU_UTIL_DATA_IMPL == ICU_UTIL_DATA_STATIC
   // Mac/Linux bundle the ICU data in.
@@ -110,6 +112,8 @@ bool InitializeICU(const char* icu_data_file) {
 
   UErrorCode err = U_ZERO_ERROR;
   udata_setCommonData(reinterpret_cast<void*>(g_icu_data_ptr), &err);
+  // Never try to load ICU data from files.
+  udata_setFileAccess(UDATA_ONLY_PACKAGES, &err);
   return err == U_ZERO_ERROR;
 #endif
 #endif